On 04.06.2018 11:36, Cornelia Huck wrote:
> On Wed, 30 May 2018 11:16:58 +0200
> Thomas Huth <th...@redhat.com> wrote:
>
>> With the STSI instruction, we can get the UUID of the current VM instance,
>> so we can support loading pxelinux config files via UUID in the file name,
>> too.
>>
>> Signed-off-by: Thomas Huth <th...@redhat.com>
>> ---
>> pc-bios/s390-ccw/netmain.c | 46
>> +++++++++++++++++++++++++++++++++++++++++++++-
>> 1 file changed, 45 insertions(+), 1 deletion(-)
>>
>> diff --git a/pc-bios/s390-ccw/netmain.c b/pc-bios/s390-ccw/netmain.c
>> index e84bb2b..7ece302 100644
>> --- a/pc-bios/s390-ccw/netmain.c
>> +++ b/pc-bios/s390-ccw/netmain.c
>> @@ -235,6 +235,49 @@ static void net_release(filename_ip_t *fn_ip)
>> }
>>
>> /**
>> + * Retrieve the Universally Unique Identifier of the VM.
>> + * @return UUID string, or NULL in case of errors
>> + */
>> +static const char *get_uuid(void)
>> +{
>> + register int r0 asm("0");
>> + register int r1 asm("1");
>> + uint8_t *mem, *buf, uuid[16];
>> + int i, chk = 0;
>> + static char uuid_str[37];
>> +
>> + mem = malloc(2 * PAGE_SIZE);
>> + if (!mem) {
>> + puts("Out of memory ... can not get UUID.");
>> + return NULL;
>> + }
>> + buf = (uint8_t *)(((uint64_t)mem + PAGE_SIZE - 1) & ~(PAGE_SIZE - 1));
>> + memset(buf, 0, PAGE_SIZE);
>> +
>> + /* Get SYSIB 3.2.2 */
>> + r0 = (3 << 28) | 2;
>> + r1 = 2;
>> + asm volatile(" stsi 0(%2)\n" : : "d" (r0), "d" (r1), "a" (buf)
>> + : "cc", "memory");
>
> Maybe check for cc == 3 here, just to be safe? (We can probably assume
> a dbct >= 1 if it is successful, I think.)
Sure, I can add that check. In case it's not available, this should have
been catched by the "if (!chk)" below, but let's better be safe than
sorry here.
>> +
>> + for (i = 0; i < 16; i++) {
>> + uuid[i] = buf[8 * 4 + 12 * 4 + i];
>
> Is there some way to make this offset less magic (offset of first vmdb
> + offset of uuid inside vmdb)?
Would a comment be sufficient? Or shall I copy the SysIB_322 structure
from target/s390x/cpu.h over to the s390-ccw bios?
Thomas
